T.D. Marwitz | Geology Reports

USGS2011

Trends in relative weight of walleye stocks in Wyoming reservoirs

The relative weight ( W r ) index of body condition provided insight into the stock dynamics of walleye Stizostedion vitreum in six reservoirs in the North Platte River drainage of Wyoming. The three most upstream reservoirs are managed as both walleye and trout ( Oncorhynchus spp. and Salmo spp.) fisheries; trout are stocked annually. The three downstream reservoirs are managed for coolwater and warmwater fishes, and walleye fry are stocked almost annually in two of the reservoirs. Positive relations between stocking densities of trout and W r of walleyes and between water levels and W r of walleyes were observed. Length-related trends in W r within walleye stocks over time were related to prey availability.

Wyoming↗

USGS1996

Estimation of potential maximum biomass of trout in Wyoming streams to assist management decisions

Fishery managers can benefit from knowledge of the potential maximum biomass (PMB) of trout in streams when making decisions on the allocation of resources to improve fisheries. Resources are most likely to be expended on streams with high PMB and with large differences between PMB and currently measured biomass. We developed and tested a model that uses four easily measured habitat variables to estimate PMB (upper 90th percentile of predicted mean biomass) of trout ( Oncorhynchus spp., Salmo trutta , and Salvelinus fontinalis ) in Wyoming streams. The habitat variables were proportion of cover, elevation, wetted width, and channel gradient. The PMB model was constructed from data on 166 stream reaches throughout Wyoming and validated on an independent data set of 50 stream reaches. Prediction of PMB in combination with estimation of current biomass and information on habitat quality can provide managers with insight into the extent to which management actions may enhance trout biomass.

Wyoming↗